Pressure sensitive adhesives have long been used in the manufacture of medical tapes and dressings intended for attachment to the skin.
Pressure sensitive adhesives intended for use in attaching tapes and/or dressings to the skin must possess a number of physical, chemical and biological characteristics including (i) biological compatibility with skin over extended periods of continuous contact, (ii) biological compatibility with surgical incisions and lesions, and (iii) a bonding strength sufficient to prevent premature peeling of the tape/dressing from the skin but low enough to prevent skin irritation upon removal of the tape/dressing.
Acrylate-Based Pressure Sensitive Adhesives
Acrylate-based pressure sensitive adhesive tapes have been used for many years in medical and surgical applications. Acrylate-based pressure sensitive adhesive tapes are generally biologically compatible and provide acceptable adhesion to the skin. One such acrylate-based pressure sensitive adhesive tape having acceptable skin adhesion performance is disclosed in U.S. Pat. No. 3,121,021 issued to Copeland.
Acrylate-based pressure sensitive adhesive tapes are known to suffer from adhesion buildup after extended contact with the skin. Excessive adhesion buildup causes the tape to strip skin from the body upon removal from the skin to the point of producing moderate pain and prolonged skin irritation. U.S. Pat. No. 3,321,451 issued to Gander discloses that the inclusion of certain amine salts into an acrylate-based pressure sensitive adhesive facilitates the removal of pressure sensitive adhesive tape from the skin by permitting the bonding strength of the tape to be reduced by soaking the tape with water. U.S. Pat. No. 3,475,363, also issued to Gander, attempts to overcome the objectionable adhesion buildup associated with acrylate-based pressure sensitive adhesives by including the crosslinking agent dimethylaminoethyl methacrylate into the adhesive.
U.S. Pat. No. 3,532,652 issued to Zang discloses that the adhesion buildup observed with acrylate-based pressure sensitive adhesives is caused by the migration of body fluids, such as skin oils, into the adhesive. Zang discloses that partially crosslinking an acrylate-based pressure sensitive interpolymer adhesive with polyisocyanate overcomes the adhesion buildup problem.
U.S. Pat. No. 4,140,115 issued to Sohonefeld discloses that the skin-stripping irritation associated with the removal of acrylate-based pressure sensitive adhesive tapes can be alleviated by blending an unreacted polyol having a fatty acid ester pendant moiety into the acrylate-based pressure sensitive adhesive. We observe that such an adhesive would tend to leave objectionable residue on the skin after removal of the tape.
Crosslinking of Pressure Sensitive Adhesives
The crosslinking of acrylate-containing polymers using a photosensitive crosslinking agent, such as a benzophenone, is taught by U.S. Pat. No. 4,181,752 issued to Martens et al.
U.S. Pat. No. 4,165,266 issued to Stueben et al. discloses a pressure sensitive adhesive composition synthesized from a poly(vinyl alkyl ether), a monoacrylate monomer and a photoinitiator, such as benzophenone.
A solvent and heat resistant pressure sensitive adhesive is disclosed in a Japanese language review article authored by Toshio Okada entitled Radiation Curing of Pressure sensitive Adhesives, Volume 20, No. 611984. The pressure-sensitive adhesive is a copolymer of benzoin acrylate and an acrylate monomer, such as 2-ethylhexylacrylate, cured by exposure to ultraviolet radiation. We believe that the degree of crosslinking in such a composition would result in an adhesive having unacceptably low adhesion strength for use in securing a tape or dressing to the skin.
While the varied adhesives disclosed above provide a wide range of beneficial properties, a substantial need still exists for a low-cost, absorbent, biologically compatible, pressure sensitive adhesive useful in the manufacture of a low-profile wound dressing having a moderate capacity for absorbing wound exudate.